Such a sealing arrangement is known in particular in the case of housings of thermal turbomachines. Thermal turbomachines are usually designed as stationary gas turbines or as steam turbines with a relatively thick-walled housing in order to shield the high pressures which prevail inside from the environment. Owing to the solid design of the housing and its particular size, it is customary to design the housing in several parts and manufacture it using a casting process. The basically tubular housings are generally split in half at a so-called horizontal split joint so that the housings in question have a lower housing part and an upper housing part. At the same time, the housings have such an axial extent that they are also designed in several parts in this direction: the housings are then split at axial joints which are also referred to as vertical split joints. The regions at which both the horizontal split joint and the axial split joint meet each other are referred to as split cross-joints.
The individual housing parts are equipped with flanges which point outward at the respective housing edge and thus provide space for bores in order to permanently and reliably connect together the abutting flanges of directly adjacent housing parts by means of expansion screws.
It has, however, been shown to be the case that, owing to the high differences in temperature between room temperature and operating temperature, the housing parts are subject to the effects of thermal expansion, which can differ locally both in their behavior over time and in degree, in particular because of the arrangement of the flanges. These locally differing expansion effects can cause the housing parts to gape apart slightly at the split joints, despite them being pressed together with great force by the numerous expansion screws. This impairs the sealing of the split joints so that, in the worst-case scenario, small leaks to the outside may even occur.
At the same time, it is known, for example from EP 0 852 659 B1, to provide a ribbed seal in the flange surfaces of two abutting housing parts in order to reduce leaks from inside the housing to the outside when gaps occur.
Instead of the ribbed seals from EP 0 852 659 B1, so-called E-seals can also be used which are positioned in just one groove, seated on an opposite flange surface. It has, however, been shown that even seals of this type do not have a sufficient springback capacity to close the size of gaps that actually occur. In addition, such E-seals are very expensive, complicated to fit and also designed to be used only once so they need to be replaced after they have been used and a housing equipped with them has been opened. U-shaped seals are also known, for example from DE 102007001459 A1.
It should moreover be noted that, in thermal turbomachines of the type mentioned at the beginning, when placing the final upper housing part on a lower housing half, when said housing part is lowered it must be moved along a gap surface of the adjacent upper housing part with a precise fit as no lateral movement is possible during assembly. With respect to the vertical split joint, it is thus impossible to move the last housing part to be assembled axially, i.e. laterally, onto the other upper housing part. This assembly-related constraint means that it is not possible to use current sealing systems with the opposing grooves and seals seated therein, disclosed in EP 0 852 659 B1, at the relevant locations.